Cobalt-gold promoter for ruthenium hydrogenation catalyst as in hydrogenation of unsaturated dinitriles

ABSTRACT

Cobalt and gold in a ruthenium hydrogenation catalyst markedly increases the yield of product. A method for hydrogenating branched-chain olefinically unsaturated aliphatic dinitrile employing a ruthenium-cobalt-gold catalyst to produce saturated diamines is set forth.

This is a divisional of Ser. No. 960,798, filed November 14, 1978, nowU.S. Pat. No. 4,215,019, issued July 29, 1980.

This invention relates to hydrogenation. In one of its aspects itrelates to a novel catalyst suited for hydrogenation processes. Inanother of its aspects the invention relates to a method for thehydrogenation of organic compounds. In one of its specific agents theinvention relates to the hydrogenation of branched-chain olefinicallyunsaturated aliphatic dinitriles.

In one of its concepts the invention provides a process for thehydrogenation of an olefinically unsaturated dinitrile, e.g. a dinitrilederived from the reaction of isobutylene and acrylonitrile. In anotherof its concepts the invention provides such a method for thehydrogenation of a mixture of olefinically unsaturated dinitrilesobtained from a reaction of isobutylene and acrylonitrile, as known inthe art. Employing a catalyst comprising essentially ruthenium, cobalt,and gold. The catalyst is generally employed employing a support, e.g.gamma-alumina. In a further concept of the invention it provides amethod for preparing the herein described catalyst by contacting asuitable support, e.g. gamma-alumina support, with an aqueous solutionof a soluble ruthenium salt, e.g. ruthenium trichloride, a solublecobalt salt or compound, e.g. cobalt (II) chloride, and a soluble goldsalt, e.g. hydrogen tetrachloroaurate (III), drying the thus impregnatedsupport, preferably at reduced pressure and at a temperature not insubstantial excess over 125° C. and then reducing the thus obtained massin the presence of hydrogen.

The hydrogenation of compounds of all kinds under hydrogenationconditions and in the presence of suitable catalysts is a well-workedart. Yet, there appears to be considerable room for improvement.Especially is this so in many instances in which long time runs forhydrogenation with a catalyst are sought to be improved.

We have now discovered that by combining cobalt and gold in a rutheniumhydrogenation catalyst there can be obtained, quite surprisingly, a verylarge increase in yield of hydrogenated product. This is especially themore surprising that a ruthenium-gold catalyst, not containing cobalt,functioned considerably less well than did a ruthenium-cobalt catalystor even a catalyst having only ruthenium therein, all as evidenced bythe experimental data given herein.

The invention will now be described as it relates to the hydrogenationof a branched-chain olefinically unsaturated aliphatic dinitrile, e.g.as present in a mixture obtained from the reaction of isobutylene andacrylonitrile, known in the art.

It is an object of this invention to provide a process for thehydrogenation of a compound. It is another object of the invention toprovide a process for the hydrogenation in an improved manner of abranched-chain olefinically unsaturated aliphatic dinitrile. It is astill further object of the invention to provide a process for theimproved hydrogenation of a mixture of branched-chain olefinicallyunsaturated aliphatic dinitriles obtained from a reaction of isobutyleneand acrylonitrile.

Other aspects, concepts, objects and the several advantages of theinvention are apparent from a study of this disclosure and the appendedclaims.

According to the present invention, an unsaturated compound, e.g. anunsaturated aliphatic dinitrile, for example, a branched-chainunsaturated aliphatic dinitrile, which can be derived from a reaction ofisobutylene and acrylonitrile, is advantageously and efficientlyhydrogenated, under hydrogenation conditions, with a catalystessentially comprising ruthenium, cobalt and gold, generally impregnatedupon a suitable support, e.g. gamma-alumina.

More specifically, in a now preferred embodiment, the invention providesa process for the catalytic hydrogenation of branched-chain olefinicallyunsaturated aliphatic dinitriles in the presence of ammonia, hydrogen, adiluent, a catalyst consisting of a first component selected fromelemental ruthenium, compounds of ruthenium which are reducible byhydrogen to elemental ruthenium, and mixtures thereof and a secondcomponent selected from elemental cobalt, compounds of cobalt reducibleby hydrogen to elemental cobalt, and mixtures thereof, and a promoterconsisting of elemental gold, compounds of gold, and mixtures thereof.

The branched-chain unsaturated aliphatic dinitriles which areadvantageously and efficiently hydrogenated in accordance with theprocess of this invention are the unsaturated dinitriles of the formula:##STR1## wherein each R is independently selected from the groupconsisting of an alkylene radical and an alkylidene radical and R' is analkyl radical. Each R and R' will generally have from one to fifteencarbon atoms, preferably from one to six, and more preferably from oneto three carbon atoms. In general, the unsaturated dinitrile reactant offormula (I) will contain from seven to 30 carbon atoms, preferably fromeight to 16 carbon atoms, and more preferably from nine to 12 carbonatoms.

Representative of unsaturated reactant species of formula (I) includesuch compounds as 4-methyl-3-hexenedinitrile, 4-ethyl-3-hexenedinitrile,5-methyl-4-nonenedinitrile, 5-ethyl-4-decenedinitrile,7-methyl-6-tridecenedinitrile, 7-methyl-6-pentadecenedinitrile,12-methyl-12-tetracosenedinitrile, 10-hexyl-9-tetracosenedinitrile,2,3-dimethyl-3-hexenedinitrile, 2,4,6-trimethyl-3-heptenedinitrile,4-ethyl-6,7-dimethyl-3-octenedinitrile,2,4,6-triethyl-3-octenedinitrile,2-ethyl-4,6-dipropyl-3-octenedinitrile,2-methyl-4,6,8,10-tetrapropyl-3-dodecenedinitrile,2,4,7,9,11,13,15-heptaethyl-6-hexadecenedinitrile, and mixtures thereof.

If desired, other unsaturated dinitrile reactants can be present andeffectively hydrogenated during the hydrogenation of the unsaturateddinitriles of formula (I). Thus, in addition to the unsaturateddinitrile reactants of formula (I), the dinitrile feedstock can containone or more unsaturated dinitrile reactants of the formula: ##STR2##wherein each R" is independently selected from the group consisting ofan alkylene radical and an alkylidene radical. In general, each R" willhave from one to 15 carbon atoms, preferably from one to seven carbonatoms, and more preferably from one to four carbon atoms. The dinitrilesof formula (II) will generally contain from six to 30 carbon atoms,preferably from eight to 16 carbon atoms, and more preferably from nineto 12 carbon atoms.

Representative unsaturated dinitrile reactants of formula (II) includesuch compounds as 3-methylenehexanedinitrile,4-methyleneheptanedinitrile, 5-methylenenonanedinitrile,6-methyleneundecanedinitrile, 7-methylenetridecanedinitrile,8-methylenepentadecanedinitrile, 12-methylenetetracosanedinitrile,15-methylenenonacosanedinitrile, 2-methyl-3-methylenepentanedinitrile,2,4-dimethyl-3-methylenepentanedinitrile,2-methyl-4-methyleneoctanedinitrile,2-methyl-7-ethyl-4-methyleneoctanedinitrile,2,4,8-trimethyl-6-methylenedodecanedinitrile,2,4,8,10-tetrapropyl-6-methylenedodecanedinitrile,2,26-dimethyl-14-methyleneheptacosanedinitrile, and mixtures thereof.

Unsaturated dinitriles having a structure other than that of formulas(I) and (II) can be present during the hydrogenation reaction, ifdesired. Similarly, other compounds which may be found in the feedsource of the dinitriles of formulas (I) and (II) can be present so longas such additional compounds do not significantly adversely affect thehydrogenation of the dinitriles of formulas (I) and (II). Where otherdinitriles are present in the feedstock, the dinitriles of formula (I)will generally constitute at least 0.1 weight percent of the totaldinitriles. The significant advantages of the invention increase withincreasing concentrations of the dinitriles of formulas (I) in thefeedstock. Thus, the process of the invention is even more advantageousfor concentrations of the dinitriles of formula (I) in the feedstock ofat least 5 weight percent. The invention is considered to beparticularly advantageous for dinitrile feedstocks having aconcentration of the dinitriles of formula (I) of at least 10 weightpercent.

A presently preferred branched-chain unsaturated aliphatic dinitrilefeedstock for employment in the practice of this invention is thedinitrile reaction product mixture obtained by the reaction ofisobutylene and acrylonitrile. This dinitrile reaction product mixturegenerally comprises 5-methyl-4-nonenedinitrile,2,4-dimethyl-4-octenedinitrile, 2,4-dimethyl-3-octenedinitrile,2,4,6-trimethyl-3-heptenedinitrile, 5-methylenenonanedinitrile,2-methyl-4-methyleneoctanedinitrile,2,6-dimethyl-4-methyleneheptanedinitrile. The first four named compoundsin this mixture are of the type of formula (I), while the last threenamed compounds in this mixture are of the type of formula (II). Theweight ratio of the dinitriles of formula (I) to the dinitriles offormula (II) in this mixture is generally in the range of about 10:1 toabout 1:10.

In the practice of this invention, the catalyst hydrogenation of theunsaturated dinitrile reactant of formula (I) results primarily in theformation of saturated diamine reaction products having the formula:##STR3## wherein R and R' are as previously defined.

The catalytic hydrogenation of an unsaturated dinitrile reactant offormula (II) results primarily in the formulation of saturated diaminereaction products having the formula: ##STR4## wherein R" is aspreviously defined.

Materials that are considered to be suitable for use as the firstcatalyst component in the gold-promoted hydrogenation catalyst of thisinvention include finely divided elemental ruthenium, compounds ofruthenium which are reducible by hydrogen to finely divided elementalruthenium and mixtures thereof. Suitable reducible compounds include theoxides, halides, nitrates, oxalates, acetates, carbamates, propionates,tartrates, hydroxides, and the like and mixtures thereof. Specificexamples include elemental ruthenium, ruthenium dioxide, rutheniumtetraoxide, ruthenium trichloride, ruthenium tetrachloride, rutheniumtrinitrate, ruthenium triacetate, ruthenium (III) carbonate, rutheniumtrihydroxide, and the like and mixtures thereof.

Materials that are considered to be suitable for use as the secondcatalyst component in the gold-promoted catalyst of this inventioninclude finely divided elemental cobalt, compounds of cobalt which arereducible by hydrogen to finely divided elemental cobalt, and mixturesthereof. Suitable reducible compounds include the oxides, halides,nitrates, oxalates, acetates, carbamates, propionates, tartrates,hydroxides, and the like, and mixtures thereof. Specific examplesinclude cobalt(II) acetate, cobalt(III) acetate, cobalt(II) benzoate,cobalt(II) bromide, cobalt(II) chloride, cobalt(III) chloride,cobalt(II) hydroxide, cobalt(III) hydroxide, cobalt(II) nitrate,cobalt(II) oxide, cobalt(III) oxide, cobalt (II) oxalate, and the like,and mixtures thereof.

The amount of the second component will generally be in the range fromabout 10 to about 300 weight percent, and preferably will be in therange from about 20 to about 200 weight percent, calculated as theelement, based on the weight of the first component in the catalyst.Herein and in the claims amounts or percentages, unless otherwisequalified, are of the metals, calculated as the element.

The weight ratio of the catalyst to unsaturated dinitrile reactant in abatch reaction, based on the weight of the component metal containedtherein, can be varied as desired. For the purpose of maintainingreasonable reaction rates under economically attractive catalyticreaction kinetics, it is generally preferred in a batch reaction thatthe weight ratio of the first component to the unsaturated dinitrilereactants be maintained within a range of about 0.01:100 to about30:100, and preferably in the range of about 0.1:100 to about 20:100.

The promoter used in the practice of this invention is selected fromelemental gold, compounds of gold, and mixtures thereof. Specificexamples of promoters include elemental gold, gold(I) bromide, gold(III)bromide, gold(I) chloride, gold(III) chloride, gold(III) oxide, hydrogentetrachloroaurate(III) (HAuCl₄), and the like and mixtures thereof. Theamount of gold promoter, calculated as elemental gold, utilized will bein the range from about 5 to about 200 weight percent, preferably fromabout 10 to about 100 weight percent based on the ruthenium content inthe catalyst. When a support is employed in batch process, the elementalruthenium content will generally be in the range of about 0.5 to about50 weight percent, preferably in the range of about 1 to about 10 weightpercent, based on the weight of the support. When a support is employedin a continuous process, the elemental ruthenium content will generallybe in the range of about 0.01 to about 10 weight percent, preferably inthe range of about 0.05 to about 5 weight percent, based on the weightof the support.

In the practice of this invention, it is often desirable to employcatalytic amounts of the first catalyst component, the second catalystcomponent, and the promoter supported by a solid catalyst carrier whichdoes not deleteriously affect the catalytic hydrogenation process ofthis invention. Such supports include, for example, carbon, kieselguhr,silica, alumina, silica-alumina, calcium carbonate, barium carbonate,asbestos, pumice, clays, and the like, and mixtures thereof. The supportcan be in the form of tablets, pellets, extrudates, granules, and thelike and mixtures thereof. The first catalyst component, the secondcatalyst component, and the promoter can be added to the catalystsupport by any of the methods well known in the art. For example, thesupported catalysts can be prepared by dry mixing the components or byimpregnating the support with a solution or dispersion of ruthenium andcobalt in elemental form or in the form of reducible compounds thereof,and elemental gold or compounds of gold.

The supported catalyst can be pretreated with hydrogen or other reducingagents known in the art to reduce the compounds, or such reduction canbe achieved in the hydrogenation reactor.

Generally speaking, one skilled in this art in possession of thisdisclosure, having studied the same, will be able to apply its conceptsto prepare a catalyst suited to his purpose including the determinationof the respective proportions of the catalytic ingredients and/orsupport, the basic concept of the catalyst invention being in thediscovery that gold somehow considerably and surprisingly improves thebasic ruthenium containing catalyst even when cobalt is present therein.

Any catalytic hydrogenation temperature can be employed which providesthe desired degree of catalytic efficiency in the hydrogenation of thebranched-chain unsaturated aliphatic dinitrile containing feedstock. Thehydrogenation temperatures will generally be within the range of about40° to about 250° C., preferably within the range of about 80° to about225° C., and more preferably within the range of about 100° to about200° C.

The catalytic hydrogenation of branched-chain unsaturated aliphaticdinitriles can be carried out at any hydrogen pressure wherein both theolefinic unsaturation and the nitrile groups are reduced in the pressureof ammonia, hydrogen and a suitable diluent. Generally, suitablehydrogen pressures are within the range of from about 100 to about 5,000psig, but lower or even higher hydrogen pressures can be employed.Preferably, due to economic considerations, hydrogen pressures withinthe range of about 500 to about 3,000 psig are employed. Higher hydrogenpressures may be desirable at lower reaction temperatures in order toachieve complete reduction within a reasonable reaction time.

Any time interval suited for the catalytic hydrogenation orbranched-chain unsaturated aliphatic dinitriles can be employed in thepractice of this invention. However, time intervals economicallyattractive to the process are generally within the range of about 15minutes to about 5 hours for a batch hydrogenation process. A reactiontime in the range of about 1 to about 3 hours is presently preferred inorder to insure substantially complete hydrogenation of any unsaturatedolefinic bonds in the feedstock as well as complete hydrogenation of thenitrile groups to primary amino groups. The catalytic hydrogenation ofunsaturated dinitriles in accordance with the process of this inventioncan be carried out as a continuous process at any suitable liquid hourlyspace velocity (LHSV). However, the liquid hourly space velocity rateswill generally be within the range of about 0.1 to about 20, morepreferably from about 0.5 to about 10, volumes of unsaturated dinitrilereactant plus diluent and ammonia per volume of catalyst (including thevolume of any catalyst support if any is present) per hour.

While any suitable diluent can be employed in the process of thisinvention, the diluent will generally be selected from the classconsisting of unsubstituted tertiary alkanols containing from 4 to 12carbon atoms per molecule, unsubstituted acyclic and unsubstitutedcyclic ethers having from 4 to 12 carbon atoms per molecule, andsaturated hydrocarbons having 4 to 12 carbon atoms per molecule, andmixtures thereof. The term "unsubstituted" signifies that there are nosubstituents other than hydrocarbyl radicals. Examples of suitabletertiary alkanol diluents include 2-methyl-2-propanol,2-methyl-2-butanol, 3-ethyl-3-hexanol, 3-ethyl-3-pentanol,3,7-dimethyl-3-octanol, 3-ethyl-3-decanol, and the like, and mixturesthereof. Examples of alkanes and cycloalkanes include butane, pentane,hexane, decane, dodecane, cyclobutane, cyclopentane, cyclohexane,cyclodecane, cyclododecane, 2-methylbutane, methylcyclopentane,2,2,4-trimethylpentane, and mixtures thereof. Examples of ethers include1,3-dioxane, 1,4-dioxane, tetrahydrofuran, 4,4-dimethyl-1,3-dioxane, andmixtures thereof. To facilitate handling of the reaction mixtures, theweight ratio of unsaturated dinitrile reactants to diluent charged tothe reaction zone is generally within the weight ratio range of about0.001:100 to about 35:100, and is preferably in the range of about0.1:100 to about 25:100.

A secondary amine formation suppressant, preferably ammonia, is employedin the process of this invention as a means of suppressing undesirableside reactions such as the formation of secondary and tertiary amines.Any amount of secondary amine formation suppressant can be employedwhich is effective in deterring or reducing undesirable side reactions.In general, the mole ratio of secondary amine formation suppressant tocyano group (there being two cyano groups in each unsaturated dinitrile)will be in the range 1:1 to about 25:1, and preferably will be in therange of about 3:1 to about 20:1. The absence of a suppressant wouldyield inferior results. However, with gold in the catalyst these resultswould show improvement over a catalyst not containing it.

Recovery of the desired end product, the branched-chain saturatedaliphatic diamines, as well as any resulting reacton by-products, anyunconsumed reactants, ammonia, hydrogen, and/or diluents can be carriedout by any conventional separation means. In general, at the conclusionof the catalytic hydrogenation process in a batch process, the reactionzone effluent is cooled and depressurized with the recovery, if desired,of any ammonia or diluent which is vented from the reaction zoneeffluent during the depressurizing operation. The ammonia or diluent canbe returned or recycled to the hydrogenation zone if desired. Thereaction products can be separated from the catalyst by conventionalfiltration means. The filtrate containing the saturated diamines can beconveniently separated from any reaction byproducts or any diluentremaining in the filtrate by any conventional fractional distillation.

In a continuous process, the reactor effluent is depressured and thediluent and ammonia removed by distillation. The recovered diluent andammonia can be recycled to the hydrogenation zone, if desired. Thesaturated diamines can be separated from any reaction byproducts or anyremaining diluent by any conventional fractional distillation.

The saturated diamine products of this invention are useful in thepreparation of polymers. Of particular interest are the polyamides. Theterephthalamide polymers have been found to be of value for theproduction of fibers and engineering plastics.

EXAMPLES

The starting material in each of the runs in this example is a mixtureof olefinically unsaturated dinitriles prepared by the reaction ofisobutylene and acrylonitrile. This reaction mixture containsapproximately 52 weight percent 5-methylenenonanedinitrile,approximately 35 weight percent 5-methyl-4-nonenedinitrile,approximately 12 weight percent of the combination of2,4-dimethyl-4-octenedinitrile, 2-methyl-4-methyleneoctanedinitrile, and2,4-dimethyl-3-octenedinitrile, and approximately 1 weight percent ofthe combination of 2,6-dimethyl-4-methyleneheptanedinitrile and2,4,6-trimethyl-3-heptenedinitrile. For simplicity, the above describedreaction mixture will be called diadduct. Hydrogenation of both theolefinic and nitrile unsaturation of diadduct yields a saturated diaminemixture.

In each hydrogenation run, a 0.5" (12.7 mm) diameter×20" (508 mm) lengthcontinuous reactor fitted with a steam heating system and temperaturerecorder was charged with 20 g. of the supported catalyst, flushed withnitrogen, flushed with hydrogen at a rate of 1 liter per minute, andheated to 140° C. A mixture containing diadduct, 2-methyl-2-propanol,and ammonia in a weight ratio of 1/8/1 was fed to the reactor at a LHSVof about 6. The reactor conditions during hydrogenation runs were 1,500psig (10.3 MPa) pressure, 140° C., and 1 liter per minute hydrogen flow.

Samples were collected from the reactor effluent after 4 hours of runtime and after 19 hours of run time and were analyzed by vapor phasechromatography after removal of the 2-methyl-2-propanol and ammoniaunder reduced pressure.

The supported catalysts were prepared by contacting a commercialgamma-alumina support with an aqueous solution of the metal chloride(s)[ruthenium, trichloride, cobalt(II) chloride, hydrogentetrachloroaurate(III)] overnight and then removing the water in arotary evaporator with reduced pressure. The impregnated support wasdried at 125° C. under reduced pressure (about 10 mm mercury) overnightand reduced in the presence of hydrogen at 300° C. for 3 hours.

Four hydrogenation runs were carried out in which diadduct washydrogenated in the presence of various catalysts. The catalyst in run 1contained 0.5 weight % ruthenium and the catalyst in run 2 contained 0.5weight % ruthenium and 0.5 weight % cobalt. Run 3 utilized a catalystwhich contained 0.5 weight % ruthenium and 0.25 weight % gold. Run 4 wascarried out according to the present invention and utilized a catalystcontaining 0.5 weight % ruthenium, 0.5 weight % cobalt, and 0.25 weight% gold. Each percentage is based on the weight of the support. Theresults of these runs are presented in Table I.

                  TABLE I                                                         ______________________________________                                                               Saturated                                              Catalyst Composition .sup.(a)                                                                        Diamines, .sup.(b)                                     Run  Ruthenium Cobalt,   Gold,   Weight %                                     No.  Weight %  Weight %  Weight %                                                                              4 hours                                                                             19 hours                               ______________________________________                                        1    0.5       0         0       67    32                                     2    0.5       0.5       0       80    69                                     3    0.5       0         0.25    53    .sup.(c)                               4    0.5       0.5       0.25    97    78                                     ______________________________________                                         .sup.(a) Weight % metal based on the weight of the support.                   .sup.(b) Weight % saturated diamines in the reaction product at the           indicated number of hours in the run. The % is calculated based on the        total product weight after removal of the diluent and ammonia.                .sup.(c) Very little product formed.                                     

The results presented in Table I show that a run 4, using a catalystcontaining ruthenium, cobalt, and gold, resulted in a much higher levelof the desired saturated diamine product than control run 1, usingruthenium only, run 2 using ruthenium and cobalt, or run 3 usingruthenium and gold. The results of run 4 are considered surprising inview of the results of run 3 in which gold appears to be detrimental toa ruthenium catalyst in the absence of cobalt.

It appears reasonable, in view of the data, to conclude that nitrile andother unsaturation hydrogenation or saturation of unsaturation in carbonto carbon bonding will be improved with the novel catalyst describedherein. This is especially so since it is known that dinitriles presentmore difficulty in their hydrogenation than most other organics ofsimilar, but not identical, structure.

Reasonable variation and modification are possible within the scope ofthe foregoing disclosure and the appended claims to the invention theessence of which is that a process for hydrogenating a compound in whichuse is made of gold to modify a ruthenium catalyst, also containingcobalt, has been found to materially yield improved hydrogenation oractivity, especially as applied to dinitriles described herein and that,therefore, a method for the hydrogenation of organic materials,especially dinitriles, also as described herein, has been set forth, ina now preferred form the catalyst comprising minor amounts of each ofthe elements mentioned.

We claim:
 1. A method for the hydrogenation of a compound whichcomprises subjecting said compound to hydrogenation conditions in thepresence of a catalyst comprising ruthenium, cobalt and gold.
 2. Amethod for the hydrogenation of a compound which comprises subjectingsaid compound to hydrogenation conditions in the presence of a catalystaccording to claim 1 wherein minor amounts of said elements arecomposited with a suitable support.
 3. A method for the hydrogenation ofa compound which comprises subjecting said compound to hydrogenationconditions in the presence of a catalyst according to claim 1 whereinthe catalyst is composited with an alumina support.
 4. A method for thehydrogenation of a compound which comprises subjecting said compound tohydrogenation conditions in the presence of a catalyst according toclaim 3 wherein the support is gamma-alumina.
 5. A method for thehydrogenation of a compound which comprises subjecting said compound tohydrogenation conditions in the presence of a catalyst according toclaim 1 wherein the catalyst is supported on a suitable support, theelemental ruthenium content is in the range of from about 0.5 to about50 weight percent based on the weight of said support, the cobalt ispresent in the approximate range of from about 10 to about 300 weightpercent based on the weight of the ruthenium in the catalyst, and thegold is present in the approximate range of from about 5 to about 200weight percent, also based on the ruthenium content of the catalyst. 6.A method for the hydrogenation of a nitrile compound which comprisessubjecting the same to hydrogenation conditions in the presence of acatalyst according to claim
 1. 7. A method for the hydrogenation of abranched-chain unsaturated aliphatic dinitrile which comprisessubjecting the same to hydrogenation conditions in the presence of acatalyst according to claim
 1. 8. A method for the hydrogenation of abranched-chain unsaturated aliphatic dinitrile which comprisessubjecting the same to hydrogenation conditions in the presence of acatalyst according to claim
 2. 9. A method for the hydrogenation of abranched-chain unsaturated aliphatic dinitrile which comprisessubjecting the same to hydrogenation conditions in the presence of acatalyst according to claim
 3. 10. A method for the hydrogenation of abranched-chain unsaturated aliphatic dinitrile which comprisessubjecting the same to hydrogenation conditions in the presence of acatalyst according to claim
 4. 11. A method for the hydrogenation of abranched-chain unsaturated aliphatic dinitrile which comprisessubjecting the same to hydrogenation conditions in the presence of acatalyst according to claim
 5. 12. A method according to claim 7 whereinthe branched-chain unsaturated aliphatic dinitrile is represented by theformula ##STR5## wherein each R is independently selected from the groupconsisting of an alkylene radical and an alkylidene radical and R' is analkyl radical.
 13. A method according to claim 12 wherein each R and R'has from 1 to 15 carbon atoms and the unsaturated dinitrile containsfrom 7 to 30 carbon atoms.
 14. A method according to claim 13 whereinthere is hydrogenated a mixture containing at least one of the followingdinitriles; 5-methyl-4-nonenedinitrile, 2,4-dimethyl-4-octenedinitrile,2,4-dimethyl-3-octenedinitrile, 2,4,6-trimethyl-3-heptenedinitrile,5-methylenenonanedinitrile, 2-methyl-4-methyleneoctanedinitrile, and2,6-dimethyl-4-methyleneheptanedinitrile.
 15. A method according toclaim 13 wherein a mixture of the following dinitriles is hydrogenated;5-methyl-4-nonenedinitrile, 2,4-dimethyl-4-octenedinitrile,2,4-dimethyl-3-octenedinitrile, 2,4,6-trimethyl-3-heptenedinitrile,5-methylenenonanedinitrile, 2-methyl-4-methyleneoctanedinitrile, and2,6-dimethyl-4-methyleneheptanedinitrile.